SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9655a8d4c5b5b758323f0cb5790d3ac6731c5992b0b01b6877e5afb82f2eab50' 
  AND token = 'yGEjxeYXqp2IziH9ggGsgPdfdZQ64cJq7nHOHoVpLsk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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