SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '2c14bec3f8fdfa7969ee412eb6236043a360f3746c2d1d15fa0cb7fc523b3e07' 
  AND token = 'GqQ4JyXDJ1H/UI3IUzZ+rsrZsXJ8vMppvB9lk5kyHCc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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