SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd493d91e0816adc21c326d2dabd171e615cd463c8803755a0880509d3a5cda9b' 
  AND token = 'smE9C7UBcUZcCd7cyatVJYW8HqpBZOyn0d1Ftj5+CnI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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