SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ab3401a34c91dc029989e4bdc9373bc44788adc8e8b387f4b595e4415655be2e' 
  AND token = '4KSDfZiLH4Kifif3389ZDyQjiFMEMyyylfj146WwnPM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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