SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '40459259e414f7a0e5a6f53256529b3d33fa58a56532aa26ea404fd6a4af6846' 
  AND token = 'rb+RD0FfRW2rEcvkW4IhxMCsTjxOYLDDrhVdgsVpnig=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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