SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '33c1e16e88bfc55a296d7c57978c930763d42fe1bdec8216a7cc8fd5fe168900' 
  AND token = 'djywxRiFMRap0gpZHHs0sdpAEwc0dXHR+78ogclKKHA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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