SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5041b3eb9644ae2a665ba0c90f864f7b6792cd9a7904debf42b1d3b877d5c727' 
  AND token = 'KRmw7GQ8wDxv/A/zVwTC6TnBZbbFjOsbSatmduKIsTs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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