SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a878be728b0e1d5e7ede664dda6e2328a385d343487dcd96bb329b06fee9b3fe' 
  AND token = 'F9+82Q+K+QFLWskxnyWdIOnWvDhqeGjQXJdzNu2fBgg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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