SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '82e936f81df94de0f578fa648753a851184c6db052d5360bfbd755794042915e' 
  AND token = 'c9zutdTq5Qiy8vxsNfyCsNkkC4EuSKeQcwXndCowglg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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