SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8c17bb3ad02d3e617f94bf6ffd7e8d458fb45cf83282bc12bff9b136335f08f' 
  AND token = 'jMyWX9uKHzXMyMs7ZsYEeTYkbSbE1MszDMkay0Jq+1M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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