SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0df9beb4ea4406322f6abd269f356834d918db1f5a15d40000789c1234958595' 
  AND token = 'WndabDyKdaw7blstck/g58zjX3yJGISB6ReiRKGGhW4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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