SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21413a8c700f5c5c245e06ebc7712ec36be7c7014811c61cc21051a481626017' 
  AND token = 'henvP0OAltkbRC2x0rVzjPulgs0/fXfE9ylLxjUyWlc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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