SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28b3bcd549220374959d61eb36b2286ff501b0acb63f990026c143df54cdd047' 
  AND token = 'RSD4rFrCkZboBRPkl2ouMxAGzQq9MBm65lb28WHOsOE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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