SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '4c713663a837efb96a6b9c82988fa90f8587fe439641c004ed6c022e8b726982' 
  AND token = '5ub86eUvoZAPFyao+lgKPWWJ4HRkOMHOLZS1qX2QuUg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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