SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6db727ef53e070bd38d56d2c0b9ecc67f0335694b76055b19284512f0e9c324' 
  AND token = 'ugn+iXSN3pA9uxT1stL39fZZ7ZmlBhmdxTFG79UEXqA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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