SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '27d37b42000af27d6ac60493e28449f8850c7a5f1da163995e64fdd63b1b25e0' 
  AND token = 'brU1d4FH8OZzKOYUXg93tinkHHWpDtlWFY77pWPFWBM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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