SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5a973a27e0ed4376fa6ed010993aa874870f9273bb4d5df848a67f86ebf164c4' 
  AND token = '3FGUOuKeHKcOkHMebvvtlRFJlwmlHzxRjLY8prBBsE4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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