SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '294612826a8c2ffdce3a7e88f81a96e122345cc94c52ecd3230c0b5a8490e9a0' 
  AND token = '3iTjj81hr6QGi7kAwsKIO5GABRCJV2p+mzQ3023tYM0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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