SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b772cea689802845c8c430c2aebc69fc7d1776511151f003faa544f61929a83' 
  AND token = '5cfVeVKyndZ7L3tu6bQuQjATyTsbOjOJmqad+CrHYJk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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