SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29a54e027b8567f9c7b4426525946d35f883c2f0f9707128663082a0c18b42d5' 
  AND token = '1JvWHpF5EH7FskRWT2v/rCMRidgqBklAn/FbzAQPHu0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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