SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e78369469e956b96a3960d52552b2bbd5a447a9e166e315c3ac7b368cf37e2b6' 
  AND token = 'wDXgg0Y46LqGjWvojGeCmXLWCwiJ/K8ejXLIKTCCqdQ=' 
  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"
    }
  }
}