SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3db57278f3c024ca2a222fee555e1e97fc7af73a6c15afc740db67c90b34cead' 
  AND token = 'fS/Crb11nTf24c7nd7DQVbtzoOtU+ZYclXY1dcfVHX0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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