SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73540b5b2269bcda97076dbd2b35800e89eed7505e9aa2fa7b6c8105cc6f5db0' 
  AND token = 'rxG8fOLxBsM4AfgwtLLir4p/u69zfBdZpwyOX4FNX5g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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