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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91f9fccfa2da3de1bf08955780cd86e55fddcb9bc25ea11e0e71d1dd0d8c280c' 
  AND token = 'MTXok/klv2ljFcXYfHGN9TCUZR3cPD6H+jKpv2wp2hk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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