SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e15e3632fdef88128a8d423ccdd8fca868f0f8d474f017c7c54bd928396657d9' 
  AND token = 'jVf0xUtnzhZKwXv2AIvvA3aF+ihXrJQ/vbKu9hgPdVo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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