SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78ffd36cfc93d8e5442a304b4e78a3be5ccb1c69d0ea2070426732caae8ac576' 
  AND token = '48+LPLr1ATnGtf3+leI9kaHxAxmK0XLHEUt0YP2k+ts=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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