SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f710d59cfeb9d87c61e491123455a0e2c642591ad8955842cdca05f2042deef1' 
  AND token = 'PFI+j0lagCRT0t52DCFvFeefX3mNiVN244uaJFuX4qw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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