SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '13b596ce5926f8e7a7f56acff72245a65adfaa445bbf43e36947f887591113b9' 
  AND token = 'Lf56SRbUTjEHOuu5TmNVKELkV5+RLdsPtOmfihAkMMs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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