SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68a53d5fdeda297ef60393cab716de2de9fa016b4ca78680c6d668867c9b29e8' 
  AND token = 'uhciwmspdCZqiExgZNF0zqVtXghV3cojGWT+Bw68gdk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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