SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8d40de0550ee2bfff2c42b1a80c2818dd8346fee641813751c72bf34f48e0ce2' 
  AND token = 'CkywyLpJCeFNAjjtj3Za55Z9mtEq+Kq+KpnPPJOCQKQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00056

JSON explain

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