SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '4f2eb67e823d0aac736fb644510ad66cac7ccd1d57fd4662a70be244c7cf376d' 
  AND token = 'zj/mOU7RfDYdZ2sw496otLRnJDDgCQezIgy8oB28TK4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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