SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3238de3a88c7a794cdef3a9816d952ad9ef03af87d873e840353595dc28a0389' 
  AND token = 'e0d8hsQ/wqHujTlxoGSEFiVOhc+gGZlrztVDwWswDOY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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