SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7f4f8b6b17ba07a11194bebc4cff29b03df683d8d19fff7924cbaeea8828256a' 
  AND token = 'V6YI+9KbCl/pHwjYXGnD8c8C2fvt7+uqdaJ+I56zVrI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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