SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e6960feecd127816e78146ce82fa81c4fe55aa4bf5b87d723a5216b5db0bd569' 
  AND token = 'jwmD3BMS5FlzKmW3n8vFY0K9N4Ayz/6HQg+GoMmligY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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