SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2a3b8f50f78769d7c648799e82f715e7401384e5a6ca37d08b4383600aaef761' 
  AND token = 'A6/mRwoS1WPLVxpHGNWHeDZO+JaG1mXz4RFhHMbLvOA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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