SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'a6c3edba8b43ca48b730190bf512a4cf13474c5d3c0e82e1dfd165b3a081ccc7' 
  AND token = 'OX8XM+t1BpRkJ+cMkSRGwYK1tJ9bHOg9lwh9aUsoSzQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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