SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '047c3989947a3a262e2b1fdedb32e6a68321db115939a0df02e8650b128f42de' 
  AND token = 'q7aZjlkmpnvtcl6RGN/5NLBlQubt6oc/rx4Uo7Lj3zY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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