SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6c54edc60463cab75683b9d150b61ecabc75129129831315ccfc85a600ca1af' 
  AND token = 'RnB4yHonXsuPVNRoaXsfQnYfi+DTB+wMSvk0b6dJ3oE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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