SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4b34c85fe0ebade3e6de53519314d215a2125dfab576c43e1f9d7a66c564acf9' 
  AND token = '0I9dCF2PfvJzLolzqeI3jcuXTKEmepzp0tQueQgaPZQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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