SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9e3df27152a7b8e78d49474ee437492689c273141cccfb9c4c0f5f323e6b4dc8' 
  AND token = '1MunkxarUsqR5trJwrVK3GQVY+RYo6KhYUo+hSvHEVA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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