SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a7e6d3597fda43c0489ba31c9de0fc92087484a18571e65fdc00b91d32e15a4c' 
  AND token = 'FnYRmjcNMh2TlpWvxmn8cc1RcmbyRYLDwZW5NcKW78A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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