SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2dadfbe19ea360dbfd14631473bfee570a7e078f21a62f2a51499f47635abd4' 
  AND token = 'jHIbyq+KbHXrrah/sTnKmNmz9WLo5EAczThK7CkgyB8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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