SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '336c7ef945c541368d89c25bc3e1da3aecd1a5147485e315b68ae5ef49966276' 
  AND token = 'MLLy7/h4KxFGmS+9gX5Lt+Gq7cWXdjsCAfb3oQkbVZo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}