SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ffabef0430290d997d1648d9028741d27a41b08d084fe35f8f8112d68a72289' 
  AND token = 'Mc7dArlMZJZCgKwPbWbNHzIpbsGUOgS7/Fpx8x18JOo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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