SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a03555f24dac34839a338d79b733e75333ce63e84380fc56bdf07ad532e6685c' 
  AND token = 'DqujXF50Ag1nucC5fPzkEFwIqGJFE8tGh0JMuefjlSs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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