SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a2ed383749bece30774db03d84e2f76612593bb209eeddb5ac5f7347dab8363f' 
  AND token = 'pTPidyo1908sTSvaCzxuSJML4B0vW33T58Nt64bVGrM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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