SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55432a591c6fd9433a24ae88712a26dabb299cdcfc9a61b38237cf6b29df4c7c' 
  AND token = '3kxa8gh/MjVhbm96FvE2yKB5k+68wPszguCQDSWae7A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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