SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5b7f5381f9eb67648c11c26056fc15eb42c948e2313d649b4f3657c5fe3092f' 
  AND token = '+RTS/LsaPJvlRDJsi9HTY4CGKsZ7D7HVtQW0Bskmq6c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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