SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '100f8f7386fff008506a207282110b2e6a4e39b04124565ec0121471150a0da9' 
  AND token = 'oXnB15mug0Ox3InTUSWQuBYuOl1mc61ogIcFTQYVLFo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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