SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ff15f9824ac0f20681c2aea46abd0d94ccd3c940687a11d4f114293a48a13a0' 
  AND token = '0uCxBwdoxdZOLBI1YHP5UBsZ6z7pEU5etiNhx0080Ow=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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