SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51a28e91fb62ca173200a211fcd1e92b2f05a32d02abf62445bd8744c1619216' 
  AND token = 'Tj25TPdB/46KxRj8LRANu2Er1jEVlooQZMB94v8axPQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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