SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3f6855746ba36414b4a40487637815517db959bb5840d7a8621d2fc02e39d90' 
  AND token = '2jZRm4NYwgqVfuuynABeh0vWVnD/Ut1wNUvym7nhnb4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00117

JSON explain

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