SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b1c2a7350e9081a9a462393179152ef56a2370afb38ed6cba091c1a866a47e31' 
  AND token = '8RxeFSkbhMUUJSijsOsNWY0zyMbQNcGu2OPdRGQ8PQo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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