SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd81bced310dbef377b7de94131dccc5c3a9fd37fa89f47f6c7cc705fa550d291' 
  AND token = 'UdU9L8cMfnAXiHBsCsJoO50sJaICvPTudaGJ3zW8tAE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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