SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27d2cb48e0c4879ab55195cbf048106419be6844f6b2eceaac9efcb042bc8e3c' 
  AND token = 'SCJWRI+0aLLq2MX6V9Js65Wv5SA23Zqjy6cD5pIs3uk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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