SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6bdaaa941713a619a0938f98948e48e5798793f4132e5a40a3b51e152d0c7101' 
  AND token = 'W9GIuLPVrGVV1Z3zV7KMrP6yhgfSQas+S+G7lMesRgc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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