SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a73c8667746c8456174b6c4ab4f9ae3aedc592d86079cf68d560eadc2c03765c' 
  AND token = 'oyi0P6jT+Vt87kA6uVWlsKUconrusDw39N5M96JGI4w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}