SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '69702a18508d9af712322c991dc2484e15839e8b37c972fd1a67746c6bd99c7a' 
  AND token = 'RzwYuKhfGrLbXFTXTFSAM0alAXqYQA9xABugxiHQc6g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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