SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '668c0a6e597319c5e795d44d055f2b4a24795145404d53cd0a8a2e7731c24dbb' 
  AND token = 'n59813Oit5f/Ij6agUdWZ+oUjCMEbHh1ri8fyHl61Jo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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