SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51880c26d6d0ade2ed4969264b568d92e13771f005eb462ec377bc86d38a9e1c' 
  AND token = 'AwZQAjUV3UNiTLiGs/3InVQdSLbLudnj1JmPlOTPBBU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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