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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18f28eb7117fe9aaeeafcc72abc28b4eb5d68af7db82cd1d77e012aee249a70f' 
  AND token = 'rpHTQpmWXqPtDuZ5QKkFhKyNJmjw8KsUpI1+ijBdfNw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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