SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9ed031e9e9f245b8924a0da9751e537b21db9f087b07837e24855880e676fd45' 
  AND token = 'UwduvdZowGqzX/UUS1fssHydL7xznyPQmLGaTwg3o1o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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