SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '7d84362d3bfc246a590c7385555abb2e3736daa0c0b175508c67455f186d8150' 
  AND token = 'jyfadZliyn2dW4rptEzCgbscvs9Tw1HXE3M5J/zzPkk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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