SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4e33a2d7b4d23ef0aacc7a70b3cc283f6ad9fbd9da65e06e8e5c49415c699924' 
  AND token = 'lKUBwb21IGqJ7ODhKvG2aV7L7IM+zfVR8sQCH8xuQYs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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