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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b20a1f6d693f6f9365cc4cbdd83f31b942eeb8f2316fe22e93def896d8eb657' 
  AND token = 'nU4FCj2jmf1q12ilcZ68KYs1yhKOdRPuvC4p5PAWGs4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}