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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bc3e68b97ef4d4a3ebcd97f828e15fb85d38a08102918175c1e63b7b8bb78771' 
  AND token = '7t9Q/bfpyzqOgDh+LWADbGGeCgCefcsXQG/6LY8Xkto=' 
  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"
    }
  }
}