SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '80f4b7fd1055038e5c8045ea3ff23648af13ea50ac9a4dd09472e575397b0d47' 
  AND token = 'M3kIF59NlULWcQvgpbRslMcY7mt34aw/1LnijeXVZO8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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