SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'eadf112895d7212130adbbdfe753e015adfd05a915d9bc7080385d954211b0d0' 
  AND token = '4A+TzBFwuyeXgJB0Y7ZZ56gJUE+Z4Ja1WNkuuDTQw6A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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