SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35f9ff87cbccd9c012bf557cab6b4b89deaa80832c47ec6e6c425a76f8c35ce4' 
  AND token = '6gY3AC2nod0ltBWvs57h0xEgHjotaQSRqrqVsJBifr4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00057

JSON explain

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