SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '6f4c775e5b48173d1cd2f2337bf01027af770df5ba3769d8489c396bd0942a1c' 
  AND token = 'SGMS5ZTN/NDjIFSrxsbP3BEFn8LUiHPWqzImn1Ka9rQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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