SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '918b3214a619c2733efe51fe7a63caed4672c9d6e4475c885069b752b3e791b0' 
  AND token = '8OmhlrsWREwoZBuZIta7OMzp7nNgFnUSHP8E8s/0lI8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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