SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '15c75319b865ff86c188a709446d181c91d9a799b36340ce5ff845cf9c44fe06' 
  AND token = 'd4nDWS5VLi/Np8ROSljimIdd4ej92Ea4h74YbRwlRUk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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