SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '1fc84a7b578d21f00e924cf1a6efcedb7dc7d57d18221758c83c6a47d971e358' 
  AND token = 'huDiVaRGjU7tD5xw8OvbLKFq27pwHQZnCnUWNDmEKDc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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