SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '34a940b79dd8b48715d0ffa0ebb2e31ae89cc5878eac83428c98eb9abb7f046c' 
  AND token = '6ZNaTvKyOj+GjgtEy4aKI8UMEXkEMyjnFJY5kiO/29Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}